The lawsuit accuses Wilton, Connecticut-based Blue Buffalo of false advertising, disparagement and unjust enrichment. It was filed in U.S. District Court in St. Louis, where Purina is based.

Messages seeking comment from Blue Buffalo were not immediately returned.

The pet food industry in recent years has seen a trend toward premium foods, with consumers showing more willingness to spend more on food perceived to be better for their animals. Sales of more expensive brands rose 68 percent from 2002 to 2012, compared with 19 percent for mid-priced brands and 8 percent for economy brands, according to Euromonitor International.

Nestle Purina has been part of the trend, reporting solid growth in its high-end “made with natural ingredients” Beyond line.

Blue Buffalo advertises that its pet foods contain natural ingredients and do not contain chicken or poultry byproduct meals. The company also says the pet foods do not contain corn, wheat or soy potential allergens for some pets.

The suit claims that testing by an independent lab and funded by Purina showed that several Blue Buffalo products contained “significant” percentages of poultry byproduct meal and corn. The suit also says several products promoted as “grain-free” contain rice hulls.

“Despite Blue Buffalo’s massive marketing barrage, Purina has discovered that Blue Buffalo and not the ‘big name’ pet food manufacturers Blue Buffalo routinely criticizes in its advertising is concealing the truth about the ingredients in its products,” the lawsuit states.

The lawsuit asks the court to force Blue Buffalo to run corrective advertising to show that its products contain chicken byproducts, and to pay damages to Nestle Purina “for all gains, profits, savings and advantages obtained by Blue Buffalo as a result of its false advertising and unfair competition.”

Nestle Purina PetCare is the nation’s largest pet food maker. It is a unit of Nestle, the Swiss-based food and drinks company.